Fuel Smell

[richard btype]

I noticed when opening the rear hatch there is whiff of fuel and I'm assuming this is from the area of the tank, I can see from the manual this is quite a busy area with the vent and various connections. Rather than a lit match! are there any other methods of detecting the source of a possible leak? The tank is the original so possibly a pin point corrosion spot.

Alternatively, I notice that the previous owner had the bumpers re chromed (they have been refitted upside down) so the tank would have been removed for this process, my plan is to drain down the tank and remove it and inspect replace all the gaskets (and refit the bumpers correctly) but any tips would be appreciated.

[Moeregaard]

Fuel smells can come from any or all of the following: fuel sender, pickup plate, perished vent lines and filler coupling, and the fuel pump on 4.2-litre cars. It's also possible that one of the banjo fittings is leaking. It takes very little fuel to stink up the entire car. If you see fuel on the ground, or if the underside of the boot has fuel residue around the sump, it's possible that the sump washer has developed a leak.

Since the sender and pickup plate are easiest to reach, check that all the screws are tight and with the proper annealed copper washers underneath. If the smell persists, or if there is visible moisture around these components, then gasket replacement is necessary--with new copper washers. I prefer to use one of the rubber-cement type of sealants (Permatex, Gaska-Cinch) rather than Blue Hylomar here. I'd also replace all of the banjo washers while I was "in the neighborhood."

The next items to check are the tank's vent pipes and filler coupling. These sit back there out of sight and out of mind, and I occasionally see cars with original bits still installed. The coupling can be a bit of a bugger to fit, but worth the effort.

On 4.2 cars, check for any wetness around the fuel-pump diaphragm and the fuel-line fittings.

[richard btype]

Mark

Thank you for the pointers, by using a short section of new rubber hose, I went around the positions you highlighted, sniffing through the tube and believe it could be the coupling hose, the lower of the clamps was not at its tightest. The clamps look original and the coupling hose is very solid. I've clamped them up to maximum and will check via a sniff test again tomorrow before in any case to order a new replacement.

Around the pump and sender aperature I could detect no trace of a fuel smell.

The car is fitted with an original key locking cap, the rubber gasket on this is very old and wooden and I may have make up a new one unless someone is making new sealing washers.

[Moeregaard]

You're very welcome, Richard. I went through this exercise with my '65 FHC a couple of times. I neglected to mention checking the drain hose that runs from the filler box to the underside of the car. If this is perished or missing, any spills at the filling station will end up inside the boot--not a good thing in my view.

[Neil1624]

Hi.

I had a similar problem when returning from the classic Le Mans this year. On investigation I found that the unions around the boot bulkhead head connector (C.18254) had come loose and were leaking. Worth checking if only to eliminate.

Best

Neil

[richard btype]

Pleased to say and fingers still crossed, that I have a result.

The coupling hose was perished and wooden, so vapour was effectively being released inside the rear section of the cabin. The new replacement hose was longer and fitted well. I took the opportunity to remove the tank, flush it out and fit an entire new set of gaskets, washers and new vent hose.

I have yet to re fill the tank with anything more than a gallon, but where as previously the smell was noticeable on opening the door, that has now disappeared completely. A pleasing outcome so far!

[cactusman]

Rubber pipes have a limited life. 5 years max based on my MGB experience. Make sure the new hose you use is approved for use as fuel line or it will dissolve in weeks.

[richard btype]

Julian

The hose came from SNG so anticipating it will be upto the job!